It's time for Biden to shut NATO's doors

• President Joe Biden's trip to the NATO leaders' summit will have significance as Biden tries to rebuild frayed alliances.
• But it would be a mistake to avoid the structural changes NATO needs, and the size of the alliance is at the top of the list.
• Daniel R. DePetris is a fellow at Defense Priorities and a foreign affairs columnist at Newsweek.

Next week, President Joe Biden will travel to Brussels for his first overseas trip. The summit with NATO heads-of-state comes two weeks after the alliance's foreign and defense ministers met to discuss the agenda.

The NATO summit will have special resonance for Biden, who entered office promising to improve Washington's relations with allies in Europe and bring the military alliance back to the center of US foreign policy.

It would be a major mistake and missed opportunity, however, if Biden and his NATO colleagues used the summit to simply wax philosophically about the so-called rules based international order and heap praise on the alliance for keeping Europe whole, free, and at peace.

Regurgitating talking points about NATO's history and legacy at the expense of difficult conversations merely delays the kind of structural change that is needed. At the top of the list is NATO's open-door policy, a principle in desperate need of reform.

Since the fall of the Berlin Wall, NATO has nearly doubled in size. A military organization that originally included 12 members is now up to 30. The alliance now covers territory from the United States to as far east and south as Turkey, constituting a massive behemoth protecting nearly 1 billion people and encompassing about half of the world's GDP.

These statistics remain a point of pride within NATO circles, as if the size of an alliance's membership is indicative of its overall strength and effectiveness.

This is not necessarily the case. While NATO is universally known as the world's oldest and most effective alliance, much of its combat power, ISR (intelligence, surveillance and reconnaissance) capability, and funding to keep the organization operational is due solely to what the US military provides.

While NATO's average defense budgets are slowly increasing over concern about Russian aggression, the US still accounts for nearly 70% of the alliance's total military expenditures.

Despite some internal opposition in NATO quarters about the Biden administration's withdrawal from Afghanistan, NATO as a whole is so reliant on US air support and logistics systems that it couldn't maintain a presence in Afghanistan even if it wanted to.

Indeed, if it weren't for the largess Washington provides, it is difficult to envision NATO maintaining its current pace of operations or continuing the kinds of (feckless) out-of-area training missions in Iraq and Afghanistan the organization has grown accustomed to. NATO-Europe continues to struggle with readiness, aging transport systems, and inadequate equipment.

Of course, nobody is anticipating a US withdrawal from NATO. Even President Donald Trump, who reportedly threatened to leave NATO, would occasionally defend the alliance.

But just because the US is a fully committed member of NATO doesn't mean it should continue to support enlargement, a concept as antiquated as it is beloved.

The remaining contestants for NATO membership are either engrossed in corruption, hold little geostrategic significance or are financially unable to meet NATO spending benchmarks. Within this context, taking in new members is a strain on the US and NATO, not a gain.

Unfortunately, enlargement for enlargement's sake is precisely what NATO, with US support, has done over the last several years. The last two countries to be inducted into the transatlantic alliance, Montenegro and North Macedonia, aren't exactly behemoths that add much of value to NATO economically or military.

At $5.5 billion, Montenegro's economy is less than one-fifth the size of Vermont's. North Macedonia, embraced into NATO last year, boasts an active duty force (7,000 personnel) smaller than the size of the Los Angeles Police Department.

Can anyone argue with a straight face that including either country is a boon to NATO rather than a burden?

For many analysts and officials in Washington, the open-door policy is a core tenet best left untouched. Challenging the concept is akin to challenging the alliance as a whole.

Yet this very same crowd is finding it increasingly hard to justify why stretching NATO's borders makes sense strategically. If anything, the opposite is true; the larger the alliance becomes, the more weight the US will have on its shoulders and the more risk the US military will incur as it is tasked with defending nations whose security and prosperity is largely irrelevant to US interests.

This is especially the case with Ukraine and Georgia, two states that are either involved in frozen conflicts with Russia or remain engulfed in intense bouts of violence with Moscow-backed separatists. Allowing either or both states to enjoy the privileges NATO membership affords all but puts US and Russian forces into conflict.

The costs of enlarging NATO's borders further to the east, which include minimizing any chance of a working relationship with Russia, simply outweighs the benefits.

During this month's NATO summit, the alliance should acknowledge the elephant in the room: NATO's open-door policy doesn't serve the interests of the alliance. And for the United States, continuing to support open doors means adding to an already cumbersome pile of security commitments.

Daniel R. DePetris is a fellow at Defense Priorities and a foreign affairs columnist at Newsweek.